President George W. Bush has acknowledged publicly for the first time that someone in his administration likely leaked the name of a CIA operative, although he also said he hopes the controversy over his decision to spare prison for a former White House aide has "run its course."

"And now we're going to move on," Bush said in a White House news conference.

The president had initially said he would fire anyone in his administration found to have publicly disclosed the identity of Valerie Plame, the wife of former Ambassador Joseph Wilson and a CIA operative. Wilson is an outspoken Iraq war critic.

Ten days ago, Bush commuted the 30-month sentence given to I. Lewis "Scooter" Libby by a federal judge in connection with the case.

Libby, the former chief of staff to Vice President Dick Cheney, had been convicted of lying and obstruction of justice in the CIA-leak case.

Bush would not directly address answer a question about whether he is disappointed in the White House officials who leaked Plame's name.

"I'm aware of the fact that perhaps somebody in the administration did disclose the name of that person," Bush said.

"I've often thought about what would have happened if that person had come forth and said, 'I did it.' Would we have had this endless hours of investigation and a lot of money being spent on this matter? But, so, it's been a tough issue for a lot of people in the White House. It's run its course and now we're going to move on."

He also defended the decision to commute Libby's sentence. "The Scooter Libby decision was, I thought, a fair and balanced decision," Bush said.